Acronym Finder
More than 100,000 acronyms and abbreviations, especially from defense, computers and telecommunications.

BioABACUS
Acronyms and abbreviations in biotechnology

EDGAR Online IPO Glossary
EDGAR Online explains all the nuances and distinctions of those tricky IPO terms.

High-Tech Dictionary
What is a magneto-optical disk? Here's a searchable computer dictionary, also with browsable lists of HTML tags, emoticons, file types, and Internet domain suffixes. From ComputerUser.com.

Jane's Defence Glossary
More than 20,0000 defense-related (oops, defence-related) terms and acronyms.

Ocean Science Acronyms
Did you know that AABW is Antarctic bottom water?

Public broadcasting acronym directory
A detailed list of organizations, from Current.

The Opaui Guide to Lists of Acronyms
A huge list of acronyms by subject.

U.S. Postal Service Abbreviations
State abbreviations, street suffixes, and other address words abbreviated.

World Wide Web Acronym and Abbreviation Server
What does UCC stand for? This site, slow as it is, defines 15,000 acronyms.